We’ve come a long way since our early ancestors roamed the primeval woodlands and grassy savannahs, but the need for open space is still hardwired into our very beings. No matter how tightly we pack ourselves into our modern cities, we can’t help yearning for a little patch of green. Parks are simply the human part of nature.

The first parks weren’t clearly demarcated green spaces as we now know them but rather informal gathering places like public wells and market squares where people of all kinds mingled. With industrialization and the massive shift of population from farming to factory work, it became clear that cities needed to provide more formal opportunities to take in the fresh air and sunshine. European aristocrats, of course, had always enjoyed their palace gardens and hunting grounds. In 1625, Marie de Médicis, the widow of France’s murdered Henry IV, made the democratic gesture of opening her gardens at Luxembourg Palace to Parisian strollers—–at least, the better-dressed ones. The British royals followed suit a dozen years later at London’s Hyde Park. By then the colonial outpost of Boston boasted its Common, a grassy oasis that housed grazing animals and the local gallows.

Birkenhead Park, across the River Mersey from Liverpool, is widely regarded as the first publicly funded park, and its opening in 1847 was a direct attempt to improve the well-being of local workers. Across the pond, U.S. cities had long set aside land for public use. William Penn marked off five public squares in Philadelphia’s 1682 street grid, four of which were later landscaped as parks. Still, for many 19th-century urbanites, a Sunday outing meant a picnic in one of the ele-gant new cemeteries on the outskirts of America’s cities. The desire to spend a few hours in a sylvan landscape was so intense that by 1860, Brooklyn’s Green-Wood Cemetery was hosting half a million visitors a year.

Its popularity wasn’t lost on New York’s city fathers, who hired Frederick Law Olmsted and Calvert Vaux to convert a swampy rectangle in the heart of Manhattan into Central Park. Olmsted, the father of American landscape architecture, was strongly influenced by Birkenhead’s picturesque vistas. He instructed engineers to shape rocky glens and glades of trees in a perfect simulation of the unspoiled countryside north of the city. By the time Central Park opened in 1859, every city in the United States wanted one.

Perhaps because New York remains the most populated city in the country, it has continued to pioneer new kinds of parks. In the 1930s and ‘40s, park commissioner Robert Moses scattered pocket parks and playgrounds around New York; recently, the city has remade both an old elevated railroad called the High Line and a busy stretch of Broadway into rather lovely refuges from the urban bustle.

Our notion of what constitutes a park has come full circle with designer Peter Latz’s transformation of August Thyssen’s blast furnace for a pig-iron plant in Duisburg-Nord, Germany, into a popular public garden. Latz’s design celebrates the furnace’s remains, which are pressed into new service as rock-climbing walls and planting beds. Other innovators are reclaiming urban crannies, from sidewalk medians to waterfront piers, for parkland. At this point, any scrap of land is viable as the next urban park.